Manifold Pressure/Vacuum Sensor: Description and Operation

The MAP sensor measures changes in the intake manifold pressure resulting from engine load and speed changes and converts this to a voltage output. By monitoring the sensor output voltage, the ECM can determine the MAP. The higher the MAP, the lower the engine vacuum and the higher the sensor output, which requires more fuel. The lower the MAP, the higher the engine vacuum and the lower the sensor output, which requires less fuel.